The invention relates to a monitoring or protection device comprising a microprocessor, a RAM, an analog-to-digital converter, to whose input analog signals are applied and designed to supply to the microprocessor digital samples representative of the analog input signals, and means for comparing each digital sample with a predetermined number of predetermined thresholds.
In state-of-the art systems, comparison of each sample to a certain number of thresholds is performed by the micro-processor, in a suitably programmed comparison sequence. Each sample supplied by the analog-to-digital converter is read by the microprocessor and may be stored in the RAM. The micro-processor then searches in an appropriate zone of the RAM for the thresholds to which the sample is to be compared and successively performs comparison of the sample with each of these thresholds. The result of this comparison can then be stored and used for subsequent processing purposes. In monitoring or protection devices, notably in built-in medium voltage cubicle protection and monitoring devices, each sample has to be compared to a large number of thresholds, whether they be thresholds intrinsic to the acquisition proper, such as non-saturation checks of physical quantity sample measurements, or thresholds connected with the protective functions to be performed, such as detection of maximum current, voltage, etc. These threshold tests are numerous, systematic and repetitive, and the processing time required for the microprocessor CPU to perform these comparisons increases as the number and complexity of the threshold zones increase.